The purpose of this proposal is to develop and validate several quantitation techniques which will be used to determine vascular blood flow and vessel size from digital angiographic image sequences. The approaches which we propose will utilize the recursive filtering techniques and equipment developed during the first three years of NIH funding (1-1-82 to 12-31-84). Initial studies suggest that the proposed techniques will be extremely accurate, easy to implement and require a small amount of processing time. Three blood flow quantitation techniques will be studied: two for use with intravenous or aortic injection of contrast material and a third, simplified, technique for use in selective angiography, including selective coronary angiography. Each of the above three techniques will require an accurate method for determining vessel dimensions, which in turn will require a method for callibrating image gray scale versus iodine concentration and vessel thickness. A simple method for making such a calibration, on a pixel-by-pixel basis for each individual patient, to account for the nonuniform spatial response due to regionally varying scattering components, and differential beam hardening also is proposed. The first year of this grant will be devoted to developing and implementing the hardware and software capabilities necessary to carry out the proposed work. During the second year flow phantoms will be used to test, modify and validate the various algorithms. During this year techniques for measuring blood flow in canines using surgically implanted doppler flow probes will be perfected in anticipation of the third year's work. The accuracy of the various blood flow measuring techniques will be established in vivo using canines in the third year. Vessels to be studied will include the femoral, renal, superior mesenteric, hepatic and carotid arteries; paired arteries will be studied bilaterally.